2D-2D stacking of graphene-like g-C₃N₄/Ultrathin Bi₄O₅Br₂ with matched energy band structure towards antibiotic removal

Highlights: • 2D-2D graphene-like g-C₃N₄/ultrathin Bi₄O₅Br₂ materials have been prepared. • With matched energy band structure, the effective charge separation can be achieved. • The holes and O₂⁻ are determined to be the main active species. - Abstract: A novel visible-light-driven 2D-2D graphene-like g-C₃N₄/ultrathin Bi₄O₅Br₂ photocatalyst was prepared via a facile solvothermal method in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C₁₆mim]Br) for the first time. FT-IR, XPS and TEM analysis results demonstrated the successful introduction of the 2D graphene-like g-C₃N₄ material to the Bi₄O₅Br₂ system. DRS and BET analysis results indicated the existence of the g-C₃N₄ could lead to the broaden absorption edge and larger surface area of the ultrathin Bi₄O₅Br₂ nanosheets. The electrochemical analysis implied a fast transfer of the interfacial electrons and low recombination rate of photogenerated charge carriers in g-C₃N₄/Bi₄O₅Br₂, which could be assigned to the sufficient and tight contact between ultrathin Bi₄O₅Br₂ and graphene-like g-C₃N₄. The quinolone antibiotic ciprofloxacin (CIP) was chosen as the target pollutant to evaluate the photocatalytic performance of the as-prepared samples under visible light irradiation. 1 wt% g-C₃N₄/Bi₄O₅Br₂ composite exhibited the highest photocatalytic degradation performance among all of the as-prepared photocatalysts. The enhancement of photocatalytic activity was attributed to the maximum contact between graphene-like g-C₃N₄ and ultrathin Bi₄O₅Br₂ material with matched energy band structure, which enable the efficient charge seperation. A possible photocatalytic mechanism also was proposed.